Drawing

Draw an arc of a circle. Takes the center of the circle,
its radius and a starting and ending point relative to the
three-o'clock position. Angles are in degrees and positive
values denote a counter clockwise motion. If the angles are
equal, an entire circle is drawn.

Draw an elliptic arc. Takes the bounding rectangle,
and a starting and ending point relative to the
three-o'clock position from the center of the rectangle.
Angles are in degrees and positive
values denote a counter clockwise motion. If the angles are
equal, an entire ellipse is drawn.

Draw a rectangle with rounded corners. The corners are
quarter circles with the given radius.
If radius is positive, the value is assumed to be the radius of the rounded corner.
If radius is negative, the absolute value is assumed to be the proportion of the smallest
dimension of the rectangle. This means that the corner can be a sensible size relative to
the size of the rectangle, and also avoids the strange effects X produces when the corners
are too big for the rectangle.